Cook fish with turmeric,salt and pepper powder. Sprinkle a few drops of water and cook. Allow this to cool. If the fish has skin and bones take it out and using a fork scramble it and keep aside.
Heat oil in a pan and add mustard seeds and when they splutter add urad dal and let it get golden brown. Add hing, curry leaves, ginger, garlic and green chilly and stir fry for a minute. Next add onion and saute till golden brown. Add chilly powder, a pinch of turmeric,cumin powder, coconut and the shredded fish. Stir fry this for two to three minutes and add chopped coriander and lemon juice. Serve with rice.